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1. Field of the Invention
The invention relates to communications systems, and in particular, to a communications system that provides Asynchronous Transfer Mode (ATM) connections and echo cancellation.
2. Description of the Prior Art
At present, long distance networks are deploying ATM systems to carry traffic. At the same time, de-regulation in the local telecommunications environment is creating the opportunity for multiple local networks to compete in the same territory. These local networks will require interconnection for calls that originate in one local network and terminate in another local network. In addition, these local networks will need access to the ATM equipment in the long distance networks.
Voice traffic that travels long distances requires echo cancellation. Echo cancellation removes reflections from the impedance mismatch caused by 4-wire/2-wire conversions at the user end.
At present there is a need for a system that provides connections between communications devices in different local networks, and between communications devices in the same local network. There is also a need for a system that provides connections with echo cancellation between local Time Division Multiplex (TDM) networks and long distance ATM networks.
The invention provides a method and communications system for providing ATM connections and echo cancellation to a communications device. The communications device could be in a local network, and the ATM connection could be in a long distance network. The invention comprises a first interworking unit, a second interworking unit, an echo canceller, and a signaling processor. The first interworking unit is connected to the signaling processor and the second interworking unit. The second interworking unit is connected to the signaling processor and to the echo canceller.
The first interworking unit accepts a first DS0 from the communications device. The signaling processor receives sionaling related to the first DS0, and processes the signaling to select a first ATM virtual connection from the first interworking unit to the second interworking unit, and to select a second ATM virtual connection from the second interworking unit to the ATM network. The signaling processor provides a first control instruction to the first interworking unit that identifies the first DS0 and the first ATM virtual connection. The signaling processor provides a second control instruction to the second interworking unit that identifies a second DS0 to the echo canceller and the second ATM virtual connection.
The first interworking unit interworks the first DS0 with the first ATM virtual connection. The second interworking unit interworks the first ATM virtual connection with the second DS0 to the echo canceller. The echo canceller cancels echo from the second DS0 and provides the second DS0 back to the second interworking unit. The second interworking unit interworks the second DS0 back from the echo canceller with the second ATM virtual connection.
In some embodiments, the invention establishes communications between the ATM network and a second communications device. The second interworking unit accepts a third ATM virtual connection from the ATM network. The signaling processor receives signaling related to the third ATM virtual connection, and processes the signaling to select a third DS0 from the second interworking unit to the echo canceller, and to select a fourth DS0 from the first interworking unit to the second communications device. The signaling processor provides a third control instruction to the second interworking unit that identifies the third ATM virtual connection and the third DS0. The signaling processor provides a fourth control instruction to the first interworking unit that identifies a fourth ATM virtual connection and the fourth DS0. The second interworking unit interworks the third ATM virtual connection with the third DS0 to the echo canceller. The echo canceller cancels echo from the third DS0 and provides the third DS0 back to the second interworking unit. The second interworking unit interworks the third DS0 back from the echo canceller with the fourth ATM virtual connection. The first interworking unit interworks the fourth ATM virtual connection with the fourth DS0.
In some embodiments, the invention establishes communications between a second communications device and a third communications device. The communications system further comprises an ATM matrix that is connected to the first interworking unit. The first interworking unit accepting a third DS0 from the second communications device. The signaling processor receives signaling related to the third DS0, and processes the signaling to select a third ATM virtual connection from the first interworking unit to the ATM matrix and back to the first interworking unit, and to select a fourth DS0 from the first interworking unit to the third communications device. The signaling processor provides a third control instruction to the first interworking unit that identifies the third DS0, the third ATM virtual connection, and the fourth DS0. The first interworking unit interworks the third DS0 with the third ATM virtual connection to the ATM matrix and interworks the third ATM virtual connection back from the ATM matrix with the fourth DS0.